| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lewistown | 1 | 6,231 | 5,971 | 0.84% | 1,089 | 6 | City |
| Denton | 2 | 208 | 203 | 0.48% | 292 | 1 | Town |
| Moore | 3 | 205 | 195 | 0.99% | 702 | 0 | Town |
| Winifred | 4 | 179 | 173 | 0.56% | 342 | 1 | Town |
| Grass Range | 5 | 115 | 110 | 0.88% | 821 | 0 | Town |
Lewistown is the largest city in Fergus County, with a population of 6,231.
Grass Range is the smallest city in Fergus County, with a population of 115.
There are 5 cities in Fergus County, Montana.